Page 633 - ACCCN's Critical Care Nursing

610 S P E C I A LT Y P R A C T I C E I N C R I T I C A L C A R E

Management Description and incidence
A patient with evidence of systemic envenomation Most stings occur during the summer months (Decem-
requires antivenom administration; monovalent antive- ber, January) in the tropical waters of northern Australia,
nom is used in preference to polyvalent antivenom when from Gladstone in Queensland around to Broome in
identity of the snake is known. Polyvalent antivenom is Western Australia, on hot, calm and overcast days when
a mixture of all monovalent antivenoms, and is therefore the jellyfish moves from the open sea to chase prey in
used for severe envenomation where the identity of the shallow water. 151,170,171 The exact incidence of stings is dif-
snake is unknown and the patient’s condition does not ficult to determine, but they are common in children.
allow time for a SVDK result, or where there is insufficient One ED reported 23 confirmed C. fleckeri stings in a
monovalent antivenom available. 163,165 Expert advice 12-month period. 172 There have been at least 63 con-
from a poison information centre may assist in identify- firmed deaths from envenomation by Chironex fleckeri in
ing the snake, based on known habitats and distribution the Indo-Pacific region.
as well as presenting symptoms.
Antivenom is always administered intravenously in a Clinical manifestations
diluted strength of 1 : 10 (or less if volume is a concern) Most stings are minor, with clinically significant stings
via an infusion. Administration is commenced slowly occurring from larger jellyfish. Stings generally occur on
while observing for signs of any adverse reaction. The the lower half of the body, and are characterised by
infusion rate can be increased if no reaction occurs, with immediate and severe pain. Pain increases in severity and
the whole initial dose administered over 15–20 minutes. may cause victims, especially children, to become inco-
The dose will vary depending on the type of antivenom, herent. While mechanisms of toxicity remain poorly
type of snake and number of bites; the use of 4–6 understood, death is thought to occur from central respi-
ampoules is not uncommon in severe envenomation. 156,165 ratory failure, or cardiotoxicity leading to A–V conduc-
Use of premedication before antivenom administration tion disturbances or paralysis of cardiac muscle. Victims
is controversial; at present the antivenom manufacturer may become unconscious before they can leave the water
does not recommend any premedication to reduce the following envenomation, and death can occur within
chance of anaphylaxis. Regardless of whether a premedi- 5 minutes. 170,171
cation is used, prepare to treat anaphylaxis. 165,169
The area of tentacle contact is seen as multiple linear
When the patient’s condition has stabilised after the lesions, purple or brown in colour. A pattern of transverse
initial dose of antivenom, the pressure immobilisation bars is usually seen along the lesions, along with an
bandage is removed, with continuous close observation intense acute inflammatory response, initially as a prompt
for any clinical deterioration caused by the release of and massive appearance of wheals followed by oedema,
venom contained by the pressure bandage. If deteriora- erythema and vesicle formation, which can lead to partial-
tion is evident, further antivenom and reapplication of or full-thickness skin death. 151,173
the pressure immobilisation bandage may be required. 163
Patients without signs of deterioration still require
ongoing observation in an HDU/ICU and repeat Assessment
pathology (coagulation studies) at 3 and 6 hours Patients presenting to ED after potential box jellyfish
post-antivenom administration. Ongoing observation sting are easily diagnosed based on the history, the pres-
and pathology studies will occur for at least 24 hours. 165 ence of pain and their skin lesions as outlined above.
Generally some form of prehospital management or
In children, management for snake bite is similar, with first aid will have been instituted. On arrival, patients
antivenom dosages the same as for an adult. Dilution with signs of clinically significant stings, alteration in
volume can be reduced (from 1 : 10 to 1 : 5) for consciousness, cardiovascular or respiratory function, or
children. 163 those with severe pain are seen immediately.
Box Jellyfish Envenomation
Chironex fleckeri (box jellyfish) is one of the world’s most Management
151
dangerous venomous animals. The jellyfish is a cubic Treatment focuses on appropriate first aid, administra-
(box-shaped) bell measuring 20–30 cm across and weigh- tion of adequate pain relief, symptomatic management
ing up to 6 kg. Four groups of tentacles, with up to 15 of cardiovascular and respiratory effects, and the admin-
tentacles in each group, can stretch up to 2 m and total istration of box jellyfish antivenom when indicated. First
length can exceed 60 m. Importantly, the animal is trans- aid measures include liberal application of vinegar to the
parent in water and is therefore difficult to identify. 170,171 sting area for 30–60 seconds. Vinegar inactivates the
The tentacles are covered with millions of stinging nema- undischarged nematocysts, so removal of any remaining
tocysts, each a spring-loaded capsule that contains a pen- tentacles should occur simultaneously to prevent further
etrating thread which discharges venom. Threads are envenomation. 151,173 Mild stings respond to the applica-
1 mm in length and capable of penetrating the dermis of tion of ice packs and simple oral analgesia, after the
adult skin. The tentacles also produce a sticky substance application of vinegar. 151,172 Patients with moderate to
that promotes adherence to a victim’s skin, causing some severe pain require IV narcotic analgesia. For patients
tentacles to be torn off and remain attached to the person, with continuing severe pain, antivenom is administered
where the nematocysts remain active. 151 along with continued parenteral analgesia. 171